When list-field changes, it should automatically change some text.

HTML Code:
<select name="part" class="input_text">
     <option value="1"> Motor </option>
     <option value="2"> Steel </option>
     <option value="3"> Glass </option>
</select>

<p>Price for each [part] is : 20 </p>
The "[part]" text should change dinamically